DNS
THE CERTIFICATE BEHIND THE CONNECTION

TLS certificate checker.

Inspect SSL/TLS certificates for any public domain or subdomain.

Checks HTTPS on port 443, including subject alternative names, validity dates and the presented chain.

SSL certificate

TLSv1.3

mail.rfc.pl · 185.174.152.202:443

Verified

Certificate chain, hostname and dates verified using this server’s CA store.

Subject
CN=d0m.rfc.pl
Issuer
C=US O=Let's Encrypt CN=YR2
Valid from
2026-08-28T17:27:44+00:00
Expires
2026-11-26T17:27:43+00:00
Days remaining
48
Serial (hex)
05E57744154D86C20BC1104B1A9AB8A7F728
Signature
RSA-SHA256
Public key
RSA 2048

Subject alternative names (SAN)

DNS:autoconfig.rfc.pl, DNS:autodiscover.rfc.pl, DNS:d0m.rfc.pl, DNS:imap.net2b.pl, DNS:imap.rfc.pl, DNS:mail.net2b.pl, DNS:mail.rfc.pl, DNS:pop.net2b.pl, DNS:pop.rfc.pl, DNS:pop3.net2b.pl, DNS:pop3.rfc.pl, DNS:smtp.net2b.pl, DNS:smtp.rfc.pl

SHA-256 fingerprint

57:AD:93:CA:08:0F:38:0A:BB:F3:2B:CA:36:3D:1F:C0:90:D5:C1:A1:CA:90:26:3B:EA:7E:78:8E:8E:79:2B:DD
Certificate extensions & PEM
keyUsage
Digital Signature, Key Encipherment
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:FALSE
subjectKeyIdentifier
06:B9:D4:C7:BF:7D:D3:62:75:E5:0C:F4:D2:9F:E9:B8:EA:5C:73:EE
authorityKeyIdentifier
40:15:2D:26:79:ED:32:20:9E:DF:9A:72:1D:D6:32:1F:81:0C:81:0C
authorityInfoAccess
CA Issuers - URI:http://yr2.i.lencr.org/
subjectAltName
DNS:autoconfig.rfc.pl, DNS:autodiscover.rfc.pl, DNS:d0m.rfc.pl, DNS:imap.net2b.pl, DNS:imap.rfc.pl, DNS:mail.net2b.pl, DNS:mail.rfc.pl, DNS:pop.net2b.pl, DNS:pop.rfc.pl, DNS:pop3.net2b.pl, DNS:pop3.rfc.pl, DNS:smtp.net2b.pl, DNS:smtp.rfc.pl
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://yr2.c.lencr.org/41.crl
ct_precert_scts
Signed Certificate Timestamp: Version : v1 (0x0) Log ID : CB:38:F7:15:89:7C:84:A1:44:5F:5B:C1:DD:FB:C9:6E: F2:9A:59:CD:47:0A:69:05:85:B0:CB:14:C3:14:58:E7 Timestamp : Aug 28 18:26:14.327 2026 GMT Extensions: none Signature : ecdsa-with-SHA256 30:45:02:21:00:F5:D0:D1:A1:9C:AD:A6:24:38:26:AA: FE:EF:0E:A3:C1:14:8C:DC:FC:13:16:A0:E7:1B:A7:5C: E7:8F:6C:68:5B:02:20:22:9F:0E:97:AD:06:37:2D:35: D6:B3:6D:4E:0F:6B:D9:AF:82:00:8F:F0:DC:C4:E3:21: 03:81:E9:E7:01:BE:C0 Signed Certificate Timestamp: Version : v1 (0x0) Log ID : A8:26:CB:E3:0A:C6:35:12:46:53:3F:E0:65:F1:4F:19: D9:6E:19:08:13:C4:1D:D9:6D:79:00:B3:12:3C:55:27 Timestamp : Aug 28 18:26:15.214 2026 GMT Extensions: 00:00:05:00:27:77:48:9E Signature : ecdsa-with-SHA256 30:45:02:21:00:A8:B0:B5:F9:5F:F2:BA:D4:4C:A9:0F: C8:3C:A9:9B:B8:B9:27:5A:43:0D:11:45:C1:A4:D4:C7: 65:4D:A7:73:C2:02:20:7F:FB:38:D9:3F:B5:F0:1B:7C: 83:90:83:4B:3C:1A:EA:67:AB:F3:A7:17:5A:96:9B:09: 33:8B:09:CF:9C:D8:2D
-----BEGIN CERTIFICATE-----
MIIFozCCBIugAwIBAgISBeV3RBVNhsILwRBLGpq4p/coMA0GCSqGSIb3DQEBCwUA
MDMxCzAJBgNVBAYTAlVTMRYwFAYDVQQKEw1MZXQncyBFbmNyeXB0MQwwCgYDVQQD
EwNZUjIwHhcNMjYwODI4MTcyNzQ0WhcNMjYxMTI2MTcyNzQzWjAVMRMwEQYDVQQD
EwpkMG0ucmZjLnBsMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqoor
oWRkVFj2V31MoAciqHEyAHar1Na8SD102zcm9Lf4jqfYN5eLMCLx0Q82ZRX8UJe4
nx43iQehN5Mkx0Yrd5xwdOyZVvYyCF34Nkt4/0+Au/2Zyh/lnUOG0IC97F8FKfE9
qYXnss9drdcPvNb+JcFGOsJZJxzjQoQgyK3s+o78f+XhQVib/eePDaHxeEwBn53x
9FqB9JWTNPVd/3KiKeJiEDfzh21VA8Uytq0Q/P3kDtamTiHpkNJpVaYSbYBnOy4R
Kx1p1twb8B0DhR9qMNrsiLtdvlnUFasWiFMBUCFRjJeNWqY0hqcXx228REavWz1p
rfLIe789mWy4lEgp9QIDAQABo4ICzTCCAskwDgYDVR0PAQH/BAQDAgWgMBMGA1Ud
JQQMMAoGCCsGAQUFBwMBMAwGA1UdEwEB/wQCMAAwHQYDVR0OBBYEFAa51Me/fdNi
deUM9NKf6bjqXHPuMB8GA1UdIwQYMBaAFEAVLSZ57TIgnt+ach3WMh+BDIEMMDMG
CCsGAQUFBwEBBCcwJTAjBggrBgEFBQcwAoYXaHR0cDovL3lyMi5pLmxlbmNyLm9y
Zy8wgckGA1UdEQSBwTCBvoIRYXV0b2NvbmZpZy5yZmMucGyCE2F1dG9kaXNjb3Zl
ci5yZmMucGyCCmQwbS5yZmMucGyCDWltYXAubmV0MmIucGyCC2ltYXAucmZjLnBs
gg1tYWlsLm5ldDJiLnBsggttYWlsLnJmYy5wbIIMcG9wLm5ldDJiLnBsggpwb3Au
cmZjLnBsgg1wb3AzLm5ldDJiLnBsggtwb3AzLnJmYy5wbIINc210cC5uZXQyYi5w
bIILc210cC5yZmMucGwwEwYDVR0gBAwwCjAIBgZngQwBAgEwLgYDVR0fBCcwJTAj
oCGgH4YdaHR0cDovL3lyMi5jLmxlbmNyLm9yZy80MS5jcmwwggEMBgorBgEEAdZ5
AgQCBIH9BIH6APgAdgDLOPcViXyEoURfW8Hd+8lu8ppZzUcKaQWFsMsUwxRY5wAA
AaBJn1a3AAAEAwBHMEUCIQD10NGhnK2mJDgmqv7vDqPBFIzc/BMWoOcbp1znj2xo
WwIgIp8Ol60GNy011rNtTg9r2a+CAI/w3MTjIQOB6ecBvsAAfgCoJsvjCsY1EkZT
P+Bl8U8Z2W4ZCBPEHdlteQCzEjxVJwAAAaBJn1ouAAgAAAUAJ3dIngQDAEcwRQIh
AKiwtflf8rrUTKkPyDypm7i5J1pDDRFFwaTUx2VNp3PCAiB/+zjZP7XwG3yDkINL
PBrqZ6vzpxdalpsJM4sJz5zYLTANBgkqhkiG9w0BAQsFAAOCAQEArPM+JJe/sZcA
v+MErYplZJkq/tDboMKwJ0yS1eJ7PQhMsDyrcNDQDu25zSn9OQZkhYQLMktfj0rR
bFhFZdPkTmUvtEItzj0j8I6wWcdVoJh7AducNSRLW3Daiq5ChdleHVbMA4v4FyUB
LYspkerM7a55857NV/qelgp2dLM3tImAv9zTMPo3MvP0ia9q0r+vPNHYpWM23nE+
85U4TuzF93CpshtQX/88Mu8VNkfyshLkIKgk92/k4zZID/cFqIu1xTnaAfNb8lmg
n3JoYBOAv44n14yHnmxDz6J6DbYAhT877aDvgyb7YIWOKqSHIlmcEye9JL0Pp4mn
MNRH2oM/xw==
-----END CERTIFICATE-----

Cipher: TLS_AES_256_GCM_SHA384 · Checked 2026-10-09T16:51:31+00:00

Server-presented chain · 2 additional certificates

Chain certificate 1

Subject
C=US O=Let's Encrypt CN=YR2
Issuer
C=US O=ISRG CN=Root YR
Valid from
2025-09-03T00:00:00+00:00
Expires
2028-09-02T23:59:59+00:00
Days remaining
694
Serial (hex)
4EBD24947E24D394802D84A52FD5B319
Signature
RSA-SHA256
Public key
RSA 2048

Subject alternative names (SAN)

No SAN extension was presented.

SHA-256 fingerprint

23:8B:85:A0:09:9C:65:B9:70:47:7D:57:24:F1:A1:D4:75:CE:50:58:CF:FE:4E:FA:87:33:89:9B:DB:86:3C:47
Certificate extensions & PEM
keyUsage
Digital Signature, Certificate Sign, CRL Sign
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:TRUE, pathlen:0
subjectKeyIdentifier
40:15:2D:26:79:ED:32:20:9E:DF:9A:72:1D:D6:32:1F:81:0C:81:0C
authorityKeyIdentifier
DE:E7:5B:60:D0:22:6D:40:28:7D:3F:0D:01:FE:A4:B5:52:B4:51:94
authorityInfoAccess
CA Issuers - URI:http://yr.i.lencr.org/
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://yr.c.lencr.org/ 
-----BEGIN CERTIFICATE-----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==
-----END CERTIFICATE-----

Chain certificate 2

Subject
C=US O=ISRG CN=Root YR
Issuer
C=US O=Internet Security Research Group CN=ISRG Root X1
Valid from
2026-05-13T00:00:00+00:00
Expires
2032-09-02T23:59:59+00:00
Days remaining
2155
Serial (hex)
F24B6D17F9D9AD7CB1C9FEA78782699F
Signature
RSA-SHA256
Public key
RSA 4096

Subject alternative names (SAN)

No SAN extension was presented.

SHA-256 fingerprint

07:26:39:D0:B1:40:D5:BF:FA:E1:6A:D9:C3:F6:CC:60:86:04:06:21:F5:1E:E6:1A:6D:46:A8:91:5C:07:CF:76
Certificate extensions & PEM
keyUsage
Certificate Sign, CRL Sign
extendedKeyUsage
TLS Web Server Authentication
basicConstraints
CA:TRUE
subjectKeyIdentifier
DE:E7:5B:60:D0:22:6D:40:28:7D:3F:0D:01:FE:A4:B5:52:B4:51:94
authorityKeyIdentifier
79:B4:59:E6:7B:B6:E5:E4:01:73:80:08:88:C8:1A:58:F6:E9:9B:6E
authorityInfoAccess
CA Issuers - URI:http://x1.i.lencr.org/
certificatePolicies
Policy: 2.23.140.1.2.1
crlDistributionPoints
Full Name: URI:http://x1.c.lencr.org/ 
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

One endpoint on port 443. Server-presented chain; no revocation, OCSP, CT or full TLS security scan.

View certificate JSON

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